Comments for Question about my birds feathers

The quaker on the left looks to be a younger bird which may account for some of the poor feather condition. Neither of the birds look that good. Besides the dishevelment of the left bird, both of them have stress marks and marks consistent with protein deficiency.

From the picture I cannot tell much more. There are several things that can occur during the hand feeding and weaning process. Interrupted or poorly scheduled feeding times, feeding to much per feeding; not feeding enough per feeding (both conditions can be prevented by monitoring their weights daily from first feeding to weaning); temperature fluctuations or inappropriate temperatures; nutritional including the hand feeding formula being below par, mixing it too thin, administering at at the wrong temperature, weaning to any food that is not a formulated or pelleted diet.

There are other contributing factors, some being unable to diagnose from a picture, and none of which I can say definitely are the cause without examining your birds.